ARC and blocks confusion

Question

I went through some of these articles about ARC in OBJ-C (https://dhoerl.wordpress.com/2013/04/23/i-finally-figured-out-weakself-and-strongself/, http://tech.pro/tutorial/1227/blocks-gcd-and-pitfalls-to-avoid, Always pass weak reference of self into block in ARC?), however these things are still unclear to me:

- (NSArray *)rightButtons{
    __typeof(self) __weak weakSelf = self;
    JAActionButton *button1 = [JAActionButton actionButtonWithTitle:@"Archive" color:kArchiveButtonColor handler:^(UIButton *actionButton, JASwipeCell*cell) {
        [cell completePinToTopViewAnimation];
        [weakSelf rightMostButtonSwipeCompleted:cell];
    }];

    return @[button1];
}

button1 is inside the lexical scope of rightButtons method. It is not a property on this class. WHY do I need to pass weakSelf to the block then? Does the compiler see button1 as self.button1 (which would then make sense to use weakSelf within the block)? How does self retain this block so that you need weakSelf?

Who said you needed weakSelf inside the block? You shouldn't in this case. Did you try it without the weak reference? Are there any problems (such as a reference cycle)? — rmaddy

Aaron Aaron · Accepted Answer · 2015-05-21T21:36:19

Self might not directly have a reference to button1, but it's possible that self has a reference to something else that has a reference to button1.

Something like: self --> view --> button1 --> self

ARC and blocks confusion

1 Answers